U.S. Publication No. 2010/0171642, owned by the assignee of the present application, proposes a remote vehicle control system for a vehicle. The system includes a mobile control node, such as a key fob having some display capability, that interacts via a bi-directional radio link with a base unit in the vehicle. The base unit is connected to the vehicle control system and allows the mobile control node to function as an input and output node on a vehicle control network, allowing remote control of the vehicle and providing functions such as remote or passive keyless entry. The remote control system also provides a vehicle location function wherein the range or distance and the bearing between the mobile control node and the vehicle can be determined and displayed on the mobile control node. The distance estimate and bearing are calculated by determining the range between the mobile control node and vehicle using a time of flight (TOF) methodology (in which distance is estimated by measuring the time taken for a signal to circumnavigate two components), and by processing the travel distance of the mobile control node and compass data in order to triangulate the position of the vehicle relative to the mobile control node.
One of the technical issues that arises in the aforementioned remote vehicle control system is the accuracy of the distance estimate in noisy environments where there are many reflection sources in the region between the vehicle and the mobile control node. In such an environment the TOF signal may follow multiple paths resulting in potentially inaccurate distance estimations from the TOF subsystem, with consequences to the performance of the remote vehicle system. It is desired to improve the accuracy of the distance estimation.